After quite a bit of researching, I’d like to get some feedback on my plans to treat a couple of rooms. The first is a small (10x10x10) control/mixing room. With a room this small, it seems like tons of bass trapping and absorption is the way to go. The only way to preserve stereo symmetry in front of the listener is to place the listener facing the window, which creates a fairly untreatable back wall. I plan on two large superchunks (24” or 34” face, floor to ceiling, using R-30) in the corners in front of the listener along with 6” panels of Safe ‘n Sound at the first reflection points on the walls. Additionally, I can put a large bass trap on top of the built-in bookshelf, 6” absorbers behind the monitors, more absorbers on the walls behind the listener, and cover most of the ceiling with 3” or 6” Safe’n’Sound (Is a full ring around the ceiling too much? Maybe just at first reflections?). The main issue is sound reflecting off the back wall; I can’t think of a way to treat that. Would another listener orientation be better? I could use a 10x11x10 room as an alternative; it is rectangular without the angled wall, but has only one full corner available for bass trapping and also makes it more difficult to run cables to the live room.

The next room I want to treat is a 15’x20’x10’ living/theater room that will hopefully double as a live room by removing a few pieces of furniture. There is an adjoining 12’x15’x10’ dining room, and an opening to the entryway. The room has some nice wood paneling that I’d like to cover as little as possible. The room sounds fairly good as a live room now, but I’m sure some absorption (not too much), bass traps, and diffusion could really make it better. I think some wide-band absorbers (6” safe ‘n sound) would work nicely on the walls and ceiling in the middle of the larger sections, but I’m struggling to figure out a good way to implement bass traps in this room (see pictures). I can easily do some bass traps on the ceiling near the entryway or in the corners of the dining room without looking too out of place, if that would help. I’m also wondering if there would be good ways to add diffusers to this room without taking too much wall space. What about doing binary amplitude diffusers on the wide-band traps (not enough surface area?)? Maybe 2-D QRDs put on the floor during recording could reduce flutter between the ceiling and large tile floor? Thanks in advance.

The reflections from the back and especially from that angled door (aimed at the listening position would worry me. If these reflections are delayed 17 msec (580 cm) or a bit more our hearing interpretes them as room acoustics, if the delay is shorter they are added with the direct sound causing smear of the stereo sound as classic theory learns us.

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As Bert mentioned, I would not make diffusion in your control room a priority. If budget is a concern you can create an accurate monitoring environment without using diffusers, and instead pour your room treatment budget into legendary bass trapping.

Instead of rugs on the floor, absorption on the ceiling is a better approach to kill flutter echo. Carpets suck high energy out of your room, but leaves energy in the mids. If you're building a neutral room, for any absorption of high frequency energy you want equal absorption of mids (and of course in a small room like this, you want insane bass absorption).

Scott's suggestions look good. You definitely want absorbers on the back wall since your room is too small to properly exploit the initial time delay gap. I would also consider soffit-mounted bass traps as a space efficient way to add extra low frequency absorption. If you're lowering the decay time in the high frequencies you need seriously bass trapping to complement it. Otherwise your room will be effectively dead for only mid and high frequencies, making low frequency modal ringing problems even more noticeable.

For your live room I think diffusers would be worthwhile (after you've applied other acoustic treatments). If you want some cheap, easy to build DIY designs, check out my site for these free sound diffuser plans: http://arqen.com/sound-diffusers/. These are modular, optimized stepped diffusers that I've designed specifically for DIY construction.